One metal delivery system that has been used in the past requires a pump to be run continuously at a constant speed to pump molten metal to a dispensing valve. The dispensing valve is operated intermittently to deliver metered amounts of metal. Several problems arise in connection with this system, such as leakage, wear on the valve parts and metal solidifying in the distribution system.
Another system that has been used employs a variable speed pump to produce a continuous flow of metal to a ladle or mold. The pump which runs continuously speed is adjusted to pump a predetermined amount of metal during each pouring cycle. This system requires adjustment or set of the pump speed or of a metering valve each time the pouring cycle is changed. When the pouring cycle is stopped or interrupted, the pump must be stopped. This results in start-up problems, including metal solidifying in the system.